Yes...sort of. Read
this thead at the Strangedogs video card flashing forum. Basically, you need -
A Radeon X1900-class card (It WON'T work with an X1950). It MUST have 512MB VRAM, not 256.
The X1900XT OEM
EFI file from strangedogs.
Read the thread to make yourself aware of the risks and pitfalls, but you can get one of these working pretty easily if you're careful.
Just out of curiosity, where do you shop for Apple products in Iran?